With a recent rise in distribution of mobile terminals, mobile terminals are now considered an essential item for modern life. Since, in addition to a voice call service unique to each portable terminal, a variety of data transmission services and various additional services are being made available via mobile terminals, mobile terminals are being transformed into functional multimedia communication devices.
Also, with developments in communication technology, a function of a messenger program previously only available on a conventional personal computer (PC). Accordingly, there is a demand for a chatting method through accessing a central message server.
Generally, an instant messaging service enables transmission and reception of chat messages between users. When a first user transmits a chat message to a second user, the second user receives the chat message from the first user through a message server. The second user also composes a chat message and transmits the chat message to the first user through the message server.
As a number of instant messaging service users is increasing, companies are attempting to earn profits through use of an instant messaging service. For example, a company may display an advertisement on a chat message window or transmit an advertising message to users through the instant messaging service.